JPS62149908A - Acrylic fibrilated fiber of high performance - Google Patents

Abstract

PURPOSE:The titled fiber that is composed of a polymer mainly containing acrylonitrile of a large intrinsic viscosity and having specific tensile strength and water filtration before fibrilation, thus being used as a substituent for asbestos in the slate production, because it has high resistance to alkali and high strength. CONSTITUTION:The objective fibers are composed of a polymer which contains more than 95wt% of acrylonitrile and has an intrinsic viscosity of over 2.5 and has more than 10g/de of tensile strength, less than 600cc of water filtration before fibrillation and 0.1-10mm length. For example, a spinning dope of the polymer is extruded into microspaces in an inert atmosphere then introduced into the coagulation bath, in other words, made into filaments yarns by the dry-wet spinning process. The resultant filament yarns are subjected to the primary drawing, heat-setting and the secondary drawing, cut into fibers of a prescribed length and fibrilated by bearing so that the water filtration comes in a prescribed range whereby the objective fibrilated fibers are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to high-performance acrylic fibrillated fibers having excellent heat resistance, chemical resistance, and mechanical strength.

(Prior Art) Asbestos has been widely used in reinforcement of cement and plastics, gaskets, friction materials, electrical insulation materials, etc.

However, the price of asbestos fluctuates widely,
Not only does the product cost 1~ fluctuate depending on the price of asbestos I~, but it has also become clear that this asbestos dust is harmful to the health of workers, so the demand for fibers that can replace asbestos has increased, and so far... Many fibers have been proposed as asbestos substitutes, including glass fibers, carbon fibers, steel fibers, olefin fibers, ``vinylon'', acrylic fibers, and aramid fibers. Among these fibers, acrylic fibers are attracting attention due to their low price, high strength, and excellent alkali resistance, and will be used in place of asbeth 1 for reinforcing cement, especially in slay 1. It is said that

However, this acrylic fiber has a significantly larger fiber diameter than Asbeth 1~, so it cannot effectively capture cement particles in the manufacturing process of slate manufactured by the papermaking method, and the wire mesh of the circular mesh cylinder The cement particles end up flowing out into the wastewater passing through the wastewater. Therefore, the acrylic fiber is not used alone, but is usually used in combination with fibrillar fibers such as waste paper pulp and wood pulp. When used in combination with these pulps, the amount of organic matter in the slate is reduced. There have been problems in that the flame retardance is decreased due to the increase in the amount of carbon dioxide, and the dimensional stability of the slate is decreased due to the hygroscopicity of the pulp.

In order to improve this drawback of acrylic fibers used as an asbestos substitute, for example, Japanese Patent Publication No. 53-46923 discloses that 60 mol% or more of acrylonitrile (hereinafter abbreviated as AN) and 40 mol% or less of vinyl carboxylic acid. It has been proposed that acrylic fibers made of a copolymer of It is necessary to mix and spin a large amount of AN-based polymer with a large amount of , which deteriorates chemical resistance such as alkali resistance and heat resistance, and also reduces mechanical strength. Therefore, asbestos substitutes such as cement reinforcement Its performance as a fiber was insufficient.

Furthermore, JP-A-56-100163 discloses that a film or tape made of an AN-based polymer having a molar concentration of AN of 33% or more and preferably 93% or less is fibrillated and is used as a reinforcing fiber. A hard material has been proposed, but this acrylic fibrillated fiber has a limited degree of fibrillation, requires the use of waste paper pulp, etc. in the papermaking process of Slay 1, and has insufficient alkali resistance. The durability of the srylate obtained was also insufficient for practical use.

(Problems to be Solved by the Invention) The object of the present invention is to provide a material having a high degree of fibrillation, that is, a low water resistance, and excellent chemical resistance such as alkali resistance, heat resistance, and mechanical strength. The purpose is to provide an acrylic fibrillated fiber, especially an acrylic fibrillated fiber that is useful as an asbestos substitute fiber.Another object of the invention is to provide an acrylic fibrillated fiber that has excellent formability in the slate manufacturing process by a paper forming method, and provides excellent reinforcement against slate. The purpose of the present invention is to provide an acrylic fibrillated fiber without any effect.

(Means for Solving the Problems) The object of the present invention is, as described in the claims, to contain at least 95% acrylonitrile and have an intrinsic viscosity of 2.5 or more. This can be achieved by using acrylic fibrillated fibers made of an acrylonitrile polymer and having a tensile strength of 10 q/d or more, a water content of 600 cc or less, and a IIi fiber length of 0.1 to 10 mm.

One of the features of the present invention is that the AN polymer constituting the acrylic fibrillated fiber is composed of a high polymerization degree polymer having an intrinsic viscosity of 2.5 or more and containing at least 95% by weight of AN. By constructing the fibers from such AN-based polymers, it is possible to obtain fibrillated fibers with high mechanical strength, especially tensile strength of 10 g/d or more, and excellent chemical resistance. Another important feature is that the acrylic fibrillated fiber has a water temperature of 6000C or less, and by having such a water temperature, it can be used for the first time in the above-mentioned paper-making method, which is the object of the present invention. This has an excellent effect on the paper-making properties of slate.

In order to obtain highly fibrillated fibers with high tensile strength and a water resistance of 600 cc or less by using an AN-based polymer having such a polymer composition and degree of polymerization, the following steps are required. It is necessary to employ specific manufacturing means.

That is, first, as a spinning method, a spinning stock solution of an AN-based polymer having the above composition and degree of polymerization is once discharged from a spinneret hole into an inert atmosphere such as air, nitrogen, argon, helium, etc., and this discharged polymer is inactivated. The fiber thread is formed by a so-called dry/wet spinning method in which the spinning solution is passed through a microscopic space in the atmosphere and then introduced into a coagulant of the spinning dope and coagulated.

That is, it has a high degree of polymerization with an intrinsic viscosity of 2.5 or more,
And from an AN-based polymer with an AN content of 95 or more, the polymer chains of the polymer are highly oriented in the fiber axis direction, and 10
High-strength fibers with a strength of ca/d or more cannot be produced by ordinary wet spinning or dry spinning, and can only be produced by applying the above-mentioned dry/wet spinning.

The obtained fibers have a fiber length of 0.1 to 10 m.
It is desirable to cut the fibers into pieces in the range of m and subject them to a beating treatment.
It is necessary to beat the material to within the range of c. In other words, the requirement that r water level is 600CC or less is
- When producing - by the papermaking method, the transient velocity of the cement slurry in the round cylinder is reduced, thereby -
This is extremely important in terms of paper forming properties, such as increasing the overarea, increasing the solid content that can be scooped onto the cylinder, and preventing cement particles from flowing out from the cylinder.

The AN-based polymer of the present invention includes monomers having copolymerizability with AN of 5% by weight or less, such as dicarboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, and lower alkyl thereof. esters,
Hydroxymethyl acrylate, hydroxyethyl acrylate-1~, hydroxyalkyl acrylate-1~ containing a carboxylic acid hydroxyl group such as hydroxymethyl methacrylate, acrylamide, methacrylamide, α-chloroacrylonitrile, hydroxyethyl acrylic acid,
There are copolymers with allylsulfonic acid, methacrylsulfonic acid, etc.

The conditions for dry/wet spinning are as follows: the above AN-based polymer is mixed with organic solvents such as dimethyl sulfoxide (DMSO), dimethyl acetamide (DMAC), and dimethyl acetamide (DMF), lysium chloride, zinc chloride, rhodan soda, etc. A concentrated aqueous solution of an inorganic salt, dissolved in an inorganic solvent such as nitric acid, has a solution viscosity of 2,000 voices or more, preferably 3
,000 to 10,000 voids, polymer) opening degree is 5 to 2
Create a 0% spinning stock solution. The distance between the spinneret surface and the coagulation bath liquid level is set within the range of 1 to 20 mm, preferably 3 to 10 mm, and the spinning solution is formed from the spinneret hole to the spinneret surface and the coagulation bath liquid surface. After discharging into a microscopic space, the resulting coagulated fiber thread is subjected to conventional methods such as water washing, solvent removal, primary stretching, drying/densification, secondary stretching, heat treatment, etc. The fibers are subjected to a post-processing step to form drawn fiber threads. The m@yarn obtained by this dry/wet spinning has extremely excellent drawability, but preferably the secondary drawing method is 1.1 times, preferably 1.5 times, under dry heat at 150 to 270°C. The total effective stretching ratio is at least 10 times, preferably 12 times or more, and the fineness is 0.1 to 10 denier (d).
, preferably within the range of 0.5 to 5 d.

The fibers thus obtained usually have a tensile strength of 10 q/d or more, a tensile modulus of 180 q/d or more, and a knot strength of 2.2.
It has mechanical properties of Ω/d or more, and has an X-ray crystal orientation of 93
% or more.

The obtained fibers have a length of 0.1 to 10 m, as described above.
After being cut into pieces, a beating means such as a beater, a refiner, a mill, a pulverizer, a ball mill, a PEI mill, and a jet air stream is applied to obtain a powder with a hardness of 600 CC or less, preferably 200 to 50 mm (as described above).
It is fibrillated to a range of 0 cc.

The acrylic fibrillated S fiber of the present invention thus obtained is formed from a polymer with a high polymerization degree and a high AN content, and is highly fibrillated, so it has excellent chemical resistance, heat resistance, and mechanical properties. Asbestos 1
- Extremely useful as an alternative IIi fiber. In particular, slate manufactured by the papermaking method exhibits excellent papermaking properties and has a large reinforcing effect even without using natural pulp with high water absorption. In addition, since it has excellent wear resistance, it exhibits excellent performance and is useful as a friction material, gasket, electrical insulation material, and reinforcing material for plastics.

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples.

In the present invention, the intrinsic viscosity, P water content, cement filtration rate, and paper formability are values measured by the following measuring method.

Put 5 mg of dry AN-based polymer with an intrinsic viscosity of near 0.0 in a flask. DMF2 containing IN sodium thiocyanate
Add 5 ml and dissolve completely.

The resulting polymer solution was measured using an Ostwald viscometer at 20
The specific viscosity is measured at °C, and the intrinsic viscosity is calculated according to the following formula.

Intrinsic viscosity - 1 + 1.32X (specific viscosity) - 110,198 r Water content: Canadian standard P water content, measured according to the measuring method specified in JIS-P-812''I.

Cement slurry filtration rate and cement permeability Niacrylic fibrillated fiber 0.6Q, Ca(OH) 20.
6g, Al1 (SO4) 30.6q1 Portland cement 28.2CI were added to water 11, and after stirring and mixing,
Anionic polyacrylamide polymer flocculant '+o
oppm was added and slowly stirred to obtain a cement slurry. Next, 50 meshes of the above cement slurry,
The mixture was filtered through a wire mesh having an area of 820 m2, and the filtration rate (CC/m1n) and the N (weight %) of the cement passing through the wire mesh were measured to determine the transmittance.

Examples 1 to 4, Comparative Examples 1 to 3 100% AN was solution polymerized in DMSO to create AN-based polymers having different intrinsic viscosities as shown in Table 1. The resulting polymer solution was heated to a viscosity of 3000 voids (45°C).
The polymer) was adjusted so that the spinning dope was prepared.

Wet spinning and dry/wet spinning were performed using these spinning stock solutions, respectively. As the coagulation bath, a 20'C155% DMSO aqueous solution was used in all methods. Also,
In the case of dry/wet spinning, the distance between the spinneret and the coagulation bath liquid level was set to 5 mm, and the distance from the coagulation liquid level to the focusing guide was 400 mm.

The obtained undrawn fiber yarn was drawn 5 times in hot water, and then
The fibers were washed with water, applied with an oil agent, and subjected to secondary stretching at a maximum stretching ratio of 90% in a dry heat tube at 180 to 20°C at 0°C to obtain the acrylic fibers shown in Table 1.

The acrylic fibers shown in Table 1 were cut into fiber lengths of 5 mm, and 20 g of the cut fibers were dispersed in approximately 101 parts of water.
Then, it was passed through a single disc refiner with a clearance of 0.1 mm to form fibrils.

The fiber length of the obtained acrylic fibrillated fibers was distributed in the range of about 0.1 to 5 mm, depending on the fiber length of the acrylic fibers before fibrillation. In addition, the results of the water temperature as shown in Table 1 were obtained. Next, the filtration rate and cement permeability of Cement 1 to slurry containing acrylic fibrillated fibers were measured, and the papermaking properties of the acrylic fibrillated fibers were evaluated. Table 2 shows the measurement results of the filtration rate and cement permeability of cement slurry using these acrylic fibrillated fibers.

Fibrillated fibers obtained from high-strength acrylic fibers made from the high polymerization degree polymer of the present invention by dry/wet spinning have a) low water resistance, good fibrillation, and low filtration rate of cement slurry. It had excellent paper-making properties with low cement permeability.

Example 5 and Comparative Example 4 The acrylic fibrillated fiber with a P water content of 560 cc obtained in Example 2 and the kraft pulp with a P water content of 550 cc were each used in an amount of 10 g, and the strength obtained in Example 2 was 11.5.
g/d acrylic fiber 10Q, Ca (OH) 210
Q and Al2(304) 310q were added to 101 water and stirred, then Portland cement 460CI was added and stirred again.

Subsequently, 200 pDm of an anionic polyacrylamide polymer flocculant was added under low speed stirring.

Next, the obtained cement slurry was transferred into a 200 m x 250 m mold lined with a 50 mesh wire mesh, and after passing, it was pressed for 1 minute at a pressure of 100 K (J/cm2) to form a cement board with a thickness of about 6 mm. .Next, 20℃, 1
After curing for 1 day in 00% R1 (20% R1) and then 6 days in water at 20°C, test pieces were cut from the cement board and the bending strength in Table 2 was measured in a wet state. The cement permeability was measured in the same manner as in Example 1, and the results are shown in Table 2.

From the table, it can be seen that when the acrylic fibrillated fibers of the present invention are used, slates with high bending strength can be obtained, and the slates have excellent dry and wet dimensional stability compared to those using natural pulp.

Claims (1)

[Claims] (1) Made of an acrylonitrile polymer containing at least 95% by weight of acrylonitrile and having an intrinsic viscosity of 2.5 or more, with a tensile strength of 10g/d or more, 600cc
High performance acrylic fibrillated fibers with a freeness of: and a fiber length of 0.1-10 mm.